A Ni / Ir / IrO2 porous carbon catalyst material and its preparation method and application

Abstract

The present invention relates to a Ni / Ir / IrO2 porous carbon catalyst material, its preparation method, and its application. The porous carbon, obtained by oxidizing the precursor Ni-MOF-74, serves as a carrier, with Ir as the active center strongly adsorbed on its surface, and is used as a highly efficient alkaline catalyst. Compared with existing technologies, this invention offers significant physical and chemical advantages, including excellent electrocatalytic activity and stability in the chlorine evolution reaction, a key method for industrial chlorine production.

Description

Technical Field

[0001] The present invention belongs to the technical field of composite materials, and in particular relates to a Ni / Ir / IrO2 porous carbon catalyst material and a preparation method and application thereof. Background Art

[0002] Water is a vital resource for all life and an essential condition for social development. With the rise of industries such as petrochemicals and pharmaceuticals, the discharge of industrial wastewater has increased, resulting in serious excesses of ammonia nitrogen pollutants, which in turn damages the ecosystem of water bodies, causes water pollution phenomena such as red tides and algal blooms, and even threatens human life and health. In order to reduce the discharge of pollutants in water bodies and promote green industrial development, it is necessary to strictly limit the ammonia nitrogen content in discharged industrial wastewater. Meanwhile, electrocatalytic oxidation can produce active chlorine (Cl, CIO, etc.) through electrocatalytic chlorine evolution reactions, which can efficiently degrade ammonia nitrogen pollutants in water bodies. However, in actual treatment processes, there are still problems such as low current efficiency and high energy consumption. Therefore, preparing anodes with high chlorine evolution selectivity and long service life for use in treating industrial wastewater to increase the active chlorine production of electrocatalytic oxidation is the key to improving its ammonia nitrogen degradation performance.

[0003] Metal-organic frameworks (MOFs) are a class of microporous crystalline materials composed of organic linkers and inorganic metal ions. They have been widely used in gas storage and separation, catalysis, sensors, and drug delivery. Constructing MOF arrays on highly conductive substrates has been shown to be an effective strategy to improve CER activity because it increases the electrocatalytic active area and reaction sites. Multi-element MOFs have obvious electronic effects between different metals, which also makes them have better CER activity than single-metal MOFs. Metal-organic framework (MOF) catalysts are constructed by coordination between organic ligands and metal ions / clusters, and have inherent advantages in mechanism research and performance optimization.

[0004] The highly oxidizing and acidic environment of the chlorine evolution reaction (CER) limits the choice of anode, namely dimensionally stable anodes (DSAs), which are typically fabricated by coating a Ti substrate with active precious metal Ru / Ir oxides. DSAs are known to have high Ru or Ir content and high CER overpotentials (>90 mV), which significantly increase the cost of industrial chlorine production. Therefore, improving the CER performance of titanium-based anodes while reducing precious metal usage is of great significance for achieving sustainable development goals. Summary of the Invention

[0005] The purpose of the present invention is to provide a Ni / Ir / IrO2 porous carbon catalyst material and its preparation method and application, so as to improve its activity as a catalyst for hydrogen evolution reaction (CER) by electrolysis of water.

[0006] The purpose of the present invention can be achieved by the following technical solutions:

[0007] This study developed a combination of an oxygen carrier and a tunable metal. The porous carbon, derived from the oxidation of a precursor called Ni-MOF-74, was used as a carrier. Ir, an active center, was strongly adsorbed on its surface and used as a highly effective alkaline catalyst. Ni-MOF-74 was synthesized using a hydrothermal method, and Ir was uniformly loaded onto the MOF-74 surface by impregnation. The final material was then calcined at high temperature.

[0008] In one aspect, the present invention provides a method for preparing a Ni / Ir / IrO2 porous carbon material catalyst, comprising the following steps:

[0009] (1) Ni(NO3)2·6H2O and 2,5-dihydroxyterephthalic acid were dissolved in a mixed solution of N,N-dimethylformamide, ethanol, and water to obtain a brown solution;

[0010] (2) placing the brown solution obtained in step (1) into a high-pressure hydrothermal reactor for reaction, and then naturally cooling to room temperature to obtain a Ni-MOF-74 precursor solution;

[0011] (3) adding IrCl3·3H2O to the Ni-MOF-74 precursor solution obtained in step (3) and mixing them thoroughly, impregnating IrCl3 into the Ni-MOF-74 precursor, and drying;

[0012] (4) The dried intermediate product obtained in step (3) is subjected to heating and oxidation, and then cooled to obtain a Ni / Ir / IrO2 porous carbon material.

[0013] Furthermore, in step (1), the molar ratio of Ni(NO3)2·6H2O and 2,5-dihydroxyterephthalic acid is 1:(0.5-1.5), preferably, the molar ratio is 1:1, and the volume ratio of N,N-dimethylformamide, ethanol and water is 1:(0.5-1.5):(0.5-1.5), preferably, the volume ratio is 1:1:1.

[0014] Furthermore, in step (2), the reaction temperature is 80-120° C., preferably, the reaction temperature is 100° C., and the reaction time is 20-28 h, preferably, the reaction time is 24 h.

[0015] Furthermore, the mass ratio of IrCl 3 · 3H 2 O to Ni-MOF-74 contained in the Ni-MOF-74 precursor solution is 1:(1 to 9), preferably, the mass ratio is 1:1.

[0016] Furthermore, the impregnation is performed at room temperature.

[0017] Furthermore, in step (3), the immersion time is 20 to 28 hours, preferably, the immersion time is 24 hours.

[0018] Furthermore, in step (3), the drying is carried out in a vacuum environment, the drying temperature is 60-100° C., preferably, the drying temperature is 80° C., and the drying time is 20-28 h, preferably, the drying time is 24 h.

[0019] Furthermore, the temperature-raising oxidation in step (4) is carried out in an air atmosphere at a heating rate of 2 to 3°C / min, the temperature is raised to 450 to 550°C, preferably to 500°C, and kept warm for 3 to 5 hours, preferably, for 4 hours.

[0020] On the other hand, the present invention provides a Ni / Ir / IrO2 porous carbon material catalyst, which is prepared by the above-mentioned preparation method.

[0021] In a third aspect, the present invention also provides a Ni / Ir / IrO2 porous carbon material catalyst for use as a chlorine evolution catalyst in industrial chlorine production.

[0022] Compared with the prior art, the present invention has the following advantages:

[0023] (1) At 400°C, the organic framework 2,5-dihydroxyterephthalic acid in the Ni-MOF74 material decomposes, the bonds between the metal ions and the organic matter are broken, and new bonds and new substances are re-formed, destroying its skeleton structure and thus its spindle-shaped morphology. The Ir element is anchored by the nitrogen-rich carbonized Ni-MOF74 vacancies, forming stable active sites. Therefore, the method of effectively increasing the specific surface area and active sites of carbon materials by introducing Ir / IrO2 into Ni-MOF74 crystals is universal and reliable.

[0024] (2) The prepared Ni / Ir / IrO2 porous carbon material catalyst has uniformly dispersed Ir active sites that can comprehensively improve its chlorine evolution catalytic performance.

[0025] (3) The porous carbon material of the present invention is beneficial to increase the active sites of the catalyst and can be used in chlorine evolution catalyst, gas adsorption, etc. From the electrochemical characteristics, 10mAcm -2 The corresponding overpotential is 107.4 mV and the Tafel slope is 57.4 mVdec-1. The catalyst has significant physicochemical advantages and has excellent electrocatalytic activity and stability for the chlorine evolution reaction, which is a key method for industrial chlorine production. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is the electrochemical performance diagram of the chlorine evolution reaction of Ni / Ir / IrO2 porous carbon material. DETAILED DESCRIPTION

[0027] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0028] In the following examples, the commercial RuO2 and IrO2 catalysts used were purchased from Titan, with purities of 99.95% and 99.9%, respectively.

[0029] Unless otherwise specified, the rest of the raw materials, reagents or processing techniques are conventional commercial products or conventional processing techniques in the art.

[0030] Example 1

[0031] 1) Prepare a Ni-MOF-74 solution by weighing 0.8 mmol of Ni(NO₃)₂·6H₂O and 0.8 mmol of 2,5-dihydroxyterephthalic acid (molar ratio of 1:1) and dissolving them in a mixture of 5 mL of N,N-dimethylformamide, 5 mL of ethanol, and 5 mL of water. Stir magnetically to obtain a fully dissolved solution.

[0032] 2) Hydrothermal preparation of Ni-MOF-74 precursor solution: The brown solution obtained at room temperature was poured into a polytetrafluoroethylene-lined reactor, placed in a high-pressure hydrothermal reactor, and heated to 100°C in an oven for 24 h;

[0033] 3) Precursor Impregnation: Add 50 mg of IrCl3·3H2O (the mass ratio of Ni-MOF-74 precursor to IrCl3·3H2O is 1:1) to the Ni-MOF-74 precursor solution cooled to room temperature and magnetically stir for 24 hours. Place the brown solution in a beaker and stir thoroughly. Then, soak at room temperature for 24 hours. Then, place the mixed solution in a vacuum oven and dry it for 24 hours.

[0034] 4) Calcination: The crucible containing the dried precursor was placed in a muffle furnace, heated to 500°C at a heating rate of 2°C / min in an air atmosphere, kept at this temperature for 4 h, and then naturally cooled to room temperature to obtain a Ni / Ir / IrO2 porous carbon material.

[0035] 5) CER electrocatalytic performance test: The electrochemical performance test of Ni / Ir / IrO2 porous carbon materials was carried out in 0.1M sodium chloride electrolyte at a scan rate of 10mV / s, with RHE as the reference electrode and an electrochemical window scanning range of 0.7-1.8V. The 10mAcm -2 The corresponding overpotential is 117.4mV. (e.g. Figure 1 shown)

[0036] Example 2

[0037] (1) Prepare Ni-MOF-74 solution by weighing 0.8 mmol Ni(NO3)2·6H2O and 0.8 mmol 2,5-dihydroxyterephthalic acid (the molar ratio of Ni-MOF-74 precursor to IrCl3·3H2O is 1:1) and dissolving them in a mixture of 5 mL N,N-dimethylformamide, 5 mL ethanol, and 5 mL water. Stir magnetically to obtain a fully dissolved solution.

[0038] (2) Hydrothermal preparation of Ni-MOF-74 precursor solution: The brown solution obtained at room temperature was poured into a polytetrafluoroethylene liner, placed in a high-pressure hydrothermal reactor, heated to 100 °C in an oven, and kept warm for 24 h;

[0039] (3) Precursor impregnation: Add 50 mg of IrCl3·3H2O (the mass ratio of Ni-MOF-74 precursor to IrCl3·3H2O is 6:4) to the Ni-MOF-74 precursor solution cooled to room temperature and magnetically stir for 24 h. Place the brown solution in a beaker and stir thoroughly. Then, soak at room temperature for 24 h. Then, place the mixed solution in a vacuum oven and dry it for 24 h.

[0040] (4) Calcination: The crucible containing the dried precursor was placed in a muffle furnace and heated to 500°C at a heating rate of 2°C / min in an air atmosphere, kept at this temperature for 4 h, and then naturally cooled to room temperature to obtain Ni / Ir / IrO2 porous carbon material.

[0041] (5) CER electrocatalytic performance test: The electrochemical performance test of Ni / Ir / IrO2 porous carbon material was carried out in 0.1M sodium chloride electrolyte at a scan rate of 10mV / s, with RHE as the reference electrode and an electrochemical window scanning range of 0.7-1.8V. -2 The corresponding overpotential is 112.4 mV.

[0042] Example 3

[0043] (1) Prepare Ni-MOF-74 solution by weighing 0.8 mmol Ni(NO3)2·6H2O and 0.8 mmol 2,5-dihydroxyterephthalic acid (molar ratio of 1:1) and dissolving them in a mixture of 5 mL N,N-dimethylformamide, 5 mL ethanol, and 5 mL water. Stir magnetically to obtain a fully dissolved solution.

[0044] (2) Hydrothermal preparation of Ni-MOF-74 precursor solution: The brown solution obtained at room temperature was poured into a polytetrafluoroethylene liner, placed in a high-pressure hydrothermal reactor, heated to 100 °C in an oven, and kept warm for 24 h;

[0045] (3) Precursor impregnation: Add 50 mg of IrCl3·3H2O (the mass ratio of Ni-MOF-74 precursor to IrCl3·3H2O is 7:3) to the Ni-MOF-74 precursor solution cooled to room temperature and magnetically stir for 24 h. Place the brown solution in a beaker and stir thoroughly, then soak at room temperature for 24 h. Then, place the mixed solution in a vacuum oven and dry it for 24 h.

[0046] (4) Calcination: The crucible containing the dried precursor was placed in a muffle furnace and heated to 500°C at a heating rate of 2°C / min in an air atmosphere, kept at this temperature for 4 h, and then naturally cooled to room temperature to obtain Ni / Ir / IrO2 porous carbon material.

[0047] (5) CER electrocatalytic performance test: The electrochemical performance test of Ni / Ir / IrO2 porous carbon material was carried out in 0.1M sodium chloride electrolyte at a scan rate of 10mV / s, with RHE as the reference electrode and an electrochemical window scanning range of 0.7-1.8V. -2 The corresponding overpotential is 107.4 mV.

[0048] Example 4

[0049] (1) Prepare Ni-MOF-74 solution by weighing 0.8 mmol Ni(NO3)2·6H2O and 0.8 mmol 2,5-dihydroxyterephthalic acid (molar ratio of 1:1) and dissolving them in a mixture of 5 mL N,N-dimethylformamide, 5 mL ethanol, and 5 mL water. Stir magnetically to obtain a fully dissolved solution.

[0050] (2) Hydrothermal preparation of Ni-MOF-74 precursor solution: The brown solution obtained at room temperature was poured into a polytetrafluoroethylene liner, placed in a high-pressure hydrothermal reactor, heated to 100 °C in an oven, and kept warm for 24 h;

[0051] (3) Precursor impregnation: Add 50 mg of IrCl3·3H2O (the mass ratio of Ni-MOF-74 precursor to IrCl3·3H2O is 8:2) to the Ni-MOF-74 precursor solution cooled to room temperature and magnetically stir for 24 h. Place the brown solution in a beaker and stir thoroughly. Then, soak at room temperature for 24 h. Then, place the mixed solution in a vacuum oven and dry it for 24 h.

[0052] (4) Calcination: The crucible containing the dried precursor was placed in a muffle furnace and heated to 500°C at a heating rate of 2°C / min in an air atmosphere, kept at this temperature for 4 h, and then naturally cooled to room temperature to obtain Ni / Ir / IrO2 porous carbon material.

[0053] (5) CER electrocatalytic performance test: The electrochemical performance test of Ni / Ir / IrO2 porous carbon material was carried out in 0.1M sodium chloride electrolyte at a scan rate of 10mV / s, with RHE as the reference electrode and an electrochemical window scanning range of 0.7-1.8V. -2 The corresponding overpotential is 115.4 mV.

[0054] Example 5

[0055] (1) Prepare Ni-MOF-74 solution by weighing 0.8 mmol Ni(NO3)2·6H2O and 0.8 mmol 2,5-dihydroxyterephthalic acid (molar ratio of 1:1) and dissolving them in a mixture of 5 mL N,N-dimethylformamide, 5 mL ethanol, and 5 mL water. Stir magnetically to obtain a fully dissolved solution.

[0056] (2) Hydrothermal preparation of Ni-MOF-74 precursor solution: The brown solution obtained at room temperature was poured into a polytetrafluoroethylene liner, placed in a high-pressure hydrothermal reactor, heated to 100 °C in an oven, and kept warm for 24 h;

[0057] (3) Precursor impregnation: Add 50 mg of IrCl3·3H2O (the mass ratio of Ni-MOF-74 precursor to IrCl3·3H2O is 9:1) to the Ni-MOF-74 precursor solution cooled to room temperature and magnetically stir for 24 h. Place the brown solution in a beaker and stir thoroughly. Then, soak at room temperature for 24 h. Then, place the mixed solution in a vacuum oven and dry it for 24 h.

[0058] (4) Calcination: The crucible containing the dried precursor was placed in a muffle furnace and heated to 500°C at a heating rate of 2°C / min in an air atmosphere, kept at this temperature for 4 h, and then naturally cooled to room temperature to obtain Ni / Ir / IrO2 porous carbon material.

[0059] (5) CER electrocatalytic performance test: The electrochemical performance test of Ni / Ir / IrO2 porous carbon material was carried out in 0.1M sodium chloride electrolyte at a scan rate of 10mV / s, with RHE as the reference electrode and an electrochemical window scanning range of 0.7-1.8V. -2 The corresponding overpotential is 143.4 mV.

[0060] Comparative Example 1:

[0061] Compared with Example 3, most of the steps are the same except that the calcination temperature of the muffle furnace is different.

[0062] (1) Prepare Ni-MOF-74 solution by weighing 0.8 mmol Ni(NO3)2·6H2O and 0.8 mmol 2,5-dihydroxyterephthalic acid (molar ratio of 1:1) and dissolving them in a mixture of 5 mL N,N-dimethylformamide, 5 mL ethanol, and 5 mL water. Stir magnetically to obtain a fully dissolved solution.

[0063] (2) Hydrothermal preparation of Ni-MOF-74 precursor solution: The brown solution obtained at room temperature was poured into a polytetrafluoroethylene liner, placed in a high-pressure hydrothermal reactor, heated to 100 °C in an oven, and kept warm for 24 h;

[0064] (3) Precursor impregnation: Add 50 mg of IrCl3·3H2O (mass ratio of 7:3) to the Ni-MOF-74 precursor solution cooled to room temperature and stir magnetically for 24 h. Place the brown solution in a beaker and stir thoroughly. Then, soak at room temperature for 24 h. Then, place the mixed solution in a vacuum oven and dry it for 24 h.

[0065] (4) Calcination: The crucible containing the dried precursor was placed in a muffle furnace and heated to 400°C at a heating rate of 2°C / min in an air atmosphere, kept at this temperature for 4 h, and then naturally cooled to room temperature to obtain Ni / Ir / IrO2 porous carbon material.

[0066] (5) CER electrocatalytic performance test: The electrochemical performance test of Ni / Ir / IrO2 porous carbon material was carried out in 0.1M sodium chloride electrolyte at a scan rate of 10mV / s, with RHE as the reference electrode and an electrochemical window scanning range of 0.7-1.8V. -2 The corresponding overpotential is 117.5 mV.

[0067] Comparative Example 2:

[0068] Compared with Example 3, most of the steps are the same except for the reaction temperature of the precursor.

[0069] (1) Prepare Ni-MOF-74 solution by weighing 0.8 mmol Ni(NO3)2·6H2O and 0.8 mmol 2,5-dihydroxyterephthalic acid (molar ratio of 1:1) and dissolving them in a mixture of 5 mL N,N-dimethylformamide, 5 mL ethanol, and 5 mL water. Stir magnetically to obtain a fully dissolved solution.

[0070] (2) Hydrothermal preparation of Ni-MOF-74 precursor solution: The brown solution obtained at room temperature was poured into a polytetrafluoroethylene liner, placed in a high-pressure hydrothermal reactor, heated to 120°C in an oven, and kept warm for 24 h;

[0071] (3) Precursor impregnation: Add 50 mg of IrCl3·3H2O (mass ratio of 7:3) to the Ni-MOF-74 precursor solution cooled to room temperature and stir magnetically for 24 h. Place the brown solution in a beaker and stir thoroughly. Then, soak at room temperature for 24 h. Then, place the mixed solution in a vacuum oven and dry it for 24 h.

[0072] (4) Calcination: The crucible containing the dried precursor was placed in a muffle furnace and heated to 500°C at a heating rate of 2°C / min in an air atmosphere, kept at this temperature for 4 h, and then naturally cooled to room temperature to obtain Ni / Ir / IrO2 porous carbon material.

[0073] (5) CER electrocatalytic performance test: The electrochemical performance test of Ni / Ir / IrO2 porous carbon material was carried out in 0.1M sodium chloride electrolyte at a scan rate of 10mV / s, with RHE as the reference electrode and the electrochemical window scanning range of 0.7-1.8V. -2 The corresponding overpotential is 123.7 mV.

[0074]

[0075]

[0076] like Figure 1 As shown, Figure 1 Among them, Ni@Ir / IrO2-MOF-74 (5:5) corresponds to the porous carbon material obtained in Example 1, Ni@Ir / IrO2-MOF-74 (6:4) corresponds to the porous carbon material obtained in Example 2, Ni@Ir / IrO2-MOF-74 (7:3) corresponds to the porous carbon material obtained in Example 3, Ni@Ir / IrO2-MOF-74 (8:2) corresponds to the porous carbon material obtained in Example 4, and Ni@Ir / IrO2-MOF-74 (9:1) corresponds to the porous carbon material obtained in Example 5. When the mass ratio of Ni-MOF-74 to IrCl3·3H2O is 7:3, 10m Acm -2 The corresponding overpotential is the lowest, which is 107.4mV. Figure 1 It can be seen that the overpotential of commercial RuO2 is 127.4 mV at a current density of 10 mA cm-2, and the overpotential of commercial IrO2 is 145.4 mV at a current density of 10 mA cm-2, and the catalytic performance is relatively poor.

[0077] The above description of the embodiments is intended to facilitate understanding and use of the invention by those skilled in the art. It will be apparent that those skilled in the art can readily make various modifications to these embodiments and apply the general principles described herein to other embodiments without requiring inventive effort. Therefore, the present invention is not limited to the above-described embodiments. Improvements and modifications made by those skilled in the art based on the disclosure of the present invention, without departing from the scope of the present invention, should be within the scope of protection of the present invention.

Claims

1. A method for preparing a Ni / Ir / IrO2 porous carbon material catalyst, characterized in that: The following steps are involved: (1) Dissolve Ni(NO3)2·6H2O and 2,5-dihydroxyterephthalic acid in a mixed solution of N,N-dimethylformamide, ethanol, and water to obtain a brown solution; (2) placing the brown solution obtained in step (1) into a high-pressure hydrothermal reactor for reaction, and then naturally cooling to room temperature to obtain a Ni-MOF-74 precursor solution; (3) adding IrCl3·3H2O to the Ni-MOF-74 precursor solution obtained in step (3) and thoroughly mixing, impregnating, and drying; (4) heating and oxidizing the dried intermediate product obtained in step (3), and cooling the product to obtain a Ni / Ir / IrO2 porous carbon material; In step (4), the temperature-raising oxidation is carried out in an air atmosphere at a heating rate of 2-3 °C / min, the temperature is raised to 450-550 °C, and the temperature is kept at this temperature for 3-5 hours.

2. The method for preparing a Ni / Ir / IrO2 porous carbon material catalyst according to claim 1, characterized in that: In step (1), the molar ratio of Ni(NO3)2·6H2O and 2,5-dihydroxyterephthalic acid is 1:(0.5-1.5), and the volume ratio of N,N-dimethylformamide, ethanol and water is 1:(0.5-1.5):(0.5-1.5).

3. The method for preparing a Ni / Ir / IrO2 porous carbon material catalyst according to claim 1, characterized in that: In step (2), the reaction temperature is 80-120°C and the reaction time is 20-28 hours.

4. The method for preparing a Ni / Ir / IrO2 porous carbon material catalyst according to claim 1, characterized in that: The mass ratio of IrCl3·3H2O to Ni-MOF-74 contained in the Ni-MOF-74 precursor solution is 1:(1~8).

5. The method for preparing a Ni / Ir / IrO2 porous carbon material catalyst according to claim 1, characterized in that: The impregnation was carried out at room temperature.

6. The method for preparing a Ni / Ir / IrO2 porous carbon material catalyst according to claim 1, characterized in that: In step (3), the immersion time is 20 to 28 hours.

7. The method for preparing a Ni / Ir / IrO2 porous carbon material catalyst according to claim 1, characterized in that: In step (3), the drying is carried out in a vacuum environment, the drying temperature is 60-100°C, and the drying time is 20-28 hours.

8. A Ni / Ir / IrO2 porous carbon material catalyst, prepared by the preparation method according to any one of claims 1 to 7.

9. Use of the Ni / Ir / IrO2 porous carbon material catalyst as claimed in claim 8 as a chlorine evolution catalyst in industrial chlorine production.

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